M&M

MY car is bone stock. I ran 13.0 @ 108 at a sea-level track. I think the NHRA correction factors may be a bit optimistic in my case.

FrankW

maybe someone's been using those 100 octane fuel and not telling

anywayz, what tires are you and the C55 running on?

M&M

Yeah I had a mix of 50% 102RON & 50% 93RON. I always run that at the drags. But most of the guys there do it anyway. Doesn't make much difference on an NA car, just makes the power delivery a lot smoother.

I had Toyo T1-S tyres on. The C55 was on Michelins I think & I don't know what fuel he had. He's an experienced racer so I'm sure he had good fuel. Here's the only video we've got of us together. That was my 1st run of the day & my slowest. I was getting a feel for the surface so I spun too much as can be heard in the video. But I still won by half a second.

http://64.191.54.129/mid/M3VSC55.avi

steve s

trap speeds are almost identical...160.5 vs 162.4 ...that's around 100 mph.. not so bad..

that c55 was like almost on grass trying to avoid the slick hehe

M&M

Yeah you can see he's an experienced racer by that move. I do the same when I'm in that lane. I would have preferred that lane, but anyway these things happen. The middle is very slipopery when the track is not prepped & the side has a rough cement that "bites" into your tyres & you hook up better. You can hear how much wheelspin I got on the centre.

TC32AMG

Holy Cow!! 12.9's? M&M running a 13.0 you have one fast M3

Like Improviz I used the HP calculation to figure out HP. But I use the average of the ET and the speed method and found that it gives - for my car the wheel HP. It is pretty close as I dynoed my car and the calculations were out by about 8 HP over data from 7 runs.

With M&M's 13.0 run at 108 I calculate (with the weight being 3500 lbs) that one run the car was making about 392 HP at the crank and with about 16% drivetrain loss 329 at the wheels!!

Is it possible BMW is low balling the quoted HP on M3's? Does race gas make that much of a diff?

I have seen M3's run here and the best I have seen them run is a 13.6 - 13.7 consistently (sea level ). Seen an SMC run a 14.2 consistently which I thought was sad nice car guy could not drive. is it possible to have such wide variances in 1/4 mile times? 12.8-13.7? 3 or 4 tenths at the most I thought.

M&M

Road & Track got 13.1 & Motortrend got 13.2 (I think) for the E46 M3. But those had thge stock Michelins. They suck off the line. With decent rubber you can get 13.0 in a stock M3. There are a few here that do that.

There's a guy that ran 12.8 with a stock M3 at Englishtown. Run's 12.4 now with chip, pullies, lightened a bit.

The variance in times comes from differences in:

- driver
- elevation
- temperature & humidity
- wind
- tyres
- SURFACE

I'm sure there's a few I left out.

Improviz

Sorry, but that car doesn't make 380-390 horsepower stock, and physics does work. Force = mass*acceleration, and if force and mass are stock, you're not going to hit a 111 mph trap speed in an M3, unless you've shaved 500 pounds or so off to lighten the mass. So, I'm skeptical about that speed...driver variances won't gain you 4-5 mph over the mags.

And the guy at Englishtown was still trapping in the 106-107 range, not 111. It takes a whole lot of horsepower to get 4 or 5 mph in trap speed. Maybe the correction factors are really screwed up, but from what I've seen before they're pretty accurate...are you consistently getting these trap speeds at 5000 ft?? That would be quite shocking, especially at 100% stock...I'd still have to see it in person to buy that trap speed. I'd buy 101, but not 104.

Yeah, the 108 at sea level sounds more reasonable, as it's only 1-2 mph off of what the mags got, but 104 at 5000 feet just doesn't sound right...I'll check out the video later, though...got work to do.

M&M

In the video I didn't do 104. I did that only once on my last run after I cooled the car & put ice on the intake manifold.

But I feel what you're saying. The fact that I only ran 108 at sea-level proves that the correction factor is slightly out. The reason I say VANOS compensates to a degree is because I have owned other cars besides BMW's & the time difference was more marked from the sea-level track to the 5000ft one. It was close to a second. That's what the C55 experienced. I reckon it would be a second faster at sea-level. I am only losing 0.6 seconds to altitude.

I know the MAF would detect less airflow at altitude & maybe the VANOS alters the cam timing to compensate. Also the 17% power & torque loss at altitude makes the car easier to launch on a manual. I can rev 1000rpm more & get ledd wheelspin. My 60ft times are better at altitude.

Dracco121

for what its worth im sertain i have raced that exect same c55 at westbank SA 5000 ft above sea level i was convinced that the c32 with a forced induction would cremate the c55 , I lost sure my car is a dud

steve s

yeah..most sc'd or tc'd cars won't lose too much on altitude where as n/a cars tend to suck and gasp for air. was in a rental magnum with the puny 2.7L v6 and pulling 4 fat-butts and luggage in the cali/oregon mountains...it just could not go up the mtns at wot past 75 mph...and worst thing is...a/c would cut out. hehe..

M&M

Yeah but the one advantage is that after 100mph, the lower air density more or less evens out with the power loss. But I reckon one must be scientific with something even as simple as a 1/4 mile sprint.

I shift at 8000rpm in 1st gear, & 2nd around 7900 & 3rd around 7800. That way I get into 4th early & avoid wasting time with the 3rd to 4th shift just before the line. Most M3 drivers would just redline each gear as the power peak is just before redline.

Also when the conditions are right & the times are good, powershift 2nd to 3rde & 3rd to 4th. That save around 0.1 per shift & keeps your revs up for the next gear.

Also, its important to cool the intake manifold to get cool dense air in. There's also a temp sensor just under there & that's how the ECU montors the intake temp.

Oil temp must also be cool but up to temp or the the ECU won't give you full power. I also use a ghood quality synthetic oil & change it often.

There's also a whole lot of tricks like staging shallow, warming tyres, dropping tyre pressure, etc. Point is that I'm doing this for 6 years with lots of different cars. There's ways to get times that seem impossible but its just experience.

steve s

don't suppose u have any ideas on a fwd?

reggid

i'd be interested to see your calculations to back this up!!! I am making an assumption that you have used formulas to predict times from hp and hp from trap speeds. They are not 100% correct, they are approximations only and should be treated that way because they don't consider every single variable. Yes physics does work and the car has a finite trap speed that it can achieve stock, its just that finding this speed is very complicated, maybe >111mph.
The thing is that the car has excess 'force' in first gear so all you have to do is maximise the 'force' put to the ground. You obviously know there are many factors to consider so i wouldn't rule it out so easily. Not to mention that magzines aren't always the best guide.

FrankW

I'd be kicking *** if i'm on mix of 102 and 93. So you had no idea if the other guy were running the same gas?

experienced racer doesn't mean he would run on 100+ octane gas. Well, either way you have the video to prove.

anywayz, if your car is a Euro spec than it should be a little quicker than the US version.

M&M

Yeah it is Euro spec, 343 bhp. What I meant by 93/102 is RON. I think you guys in the US use MON. I think our 102 RON is equivalent to your 99 MON. What is the compression ration on the C55?

FrankW

the best we get in California is 91 octane MON. 99-100 octane are race fuel that cost $5-6 dollar plus per gallon where the 91 is $2.17 as of now at the cheapest gas station around my area.

Fikse

forget all these correction factors.... you ran what you ran... if you want to run your car at sea level, then do so....